Enzymes

biological catalysts
speed up reactions so that the reactions happen at normal body temperature
globular proteins with tertiary or quaternary structure

Substrate

reactant
2 substrates forming 1 product or 1 substrate forming 2 products
catabolic or anabolic metabolism

Active Site

specific shape with active site in enzyme
region of enzyme where substrate will bond and reaction will occur
reaction will occur here
chemical attraction between AS and enzyme
enzyme and substrate is like lock and key

Denaturation

enzyme loses conformation and can't function
separate 2 DNA strands
extreme conditions of pH, salt concentration, and temperature cause this catalyst change reaction rate without being consumed

Immobilized Enzymes

in industry
restrict enzyme movement
commercial use of 500+ enzymes
more stable
uses biotechnology

Biotechnology

makes products like laundry detergent, textile preparation, biodegradable clothing
normal production of lactase, which breaks lactose into glucose and galactose
makes yeast, which makes lactase
helps in lactose intolerance

3 steps in catalysis

Substrate(s) bond to active site (s)
Substrate turns to a product bound to the enzyme
Active Site releases the product and can catalyze other substances

Substrate Movement

random movement in water
substrate smaller and faster than enzyme
random movement causes collision which causes enzyme-catalyzed reaction

Enzymes & Temperature

temperature increase causes enzyme efficiency to increase until a certain point
once that point is crossed, the enzyme denatures

Enzymes & pH

optimum pH of 7
activity level reduced with pH change

Enzymes & Substrate Concentration

directly proportional
until all enzymes are active
then no effect on concentration

Cofactors

nonprotein enzyme helpers
inorganic or organic
organic includes coenzymes
coenzymes include vitamins

Enzyme Inhibitors

slow down enzyme reaction rate
competitive or noncompetitive
ex. toxin, poison, pesticides, antibiotics

Competitive Inhibitor

binds to enzyme's active site
directly competes with the substrate

Competitive Inhibitor Graph

same Vmax
lower Km

Noncompetitive Inhibitor

binds to other part of enzyme
denatures it, making it less useful
same Km, lower Vmax

Noncompetitive Inhibitor Graph

same Km
lower Vmax

Enzyme Regulation

chemical chaos if cell's metabolic pathways weren't tightly regulated
cells switch genes encoding certain enzymes on and off or regulating enzyme activity

Allosteric Regulation

inhibit or stimulate enzyme
regulatory molecule binds to enzyme at one site and affects action at another

Allosteric Regulation & Inhibition

most allosteric-regulated enzymes made from polypeptide subunits
active and inactive forms
activator binding and inhibitor binding

Activator binding site

stabilizes the active form of the enzyme

Inhibitor Binding Site

stabilizes enzyme's inactive form

Feedback Inhibition

end-product of metabolic pathway shuts down the pathway
prevents a cell from wasting chemical resources by synthesizing extra product

Assumption of a Steady State

transient phase where ES concentration does not change during the reaction (dES/dt) = 0 Km
substrate concentration where V0 = (1/2) (Vmax)

Enzyme classification

uses a number system

Enzyme Classes

Oxidoreductase * transfer electrons in Redox reactions to catalyze oxidation or reduction * oxidation * reduction in electrons * increase oxidation state * reduction * increase in electrons * decrease oxidation state
Transferase * transfer functional groups between molecules
Hydrolase * break bonds by adding H2O
Lyase * elimination reactions to form double bonds * remove hydrogen and carbon
Isomerase * aka utase * intramolecular arrangements * one of the "weirder" enzymes
Ligase * join molecules with new bonds metabolism
* total of organism's chemical reactions * emergent property from cellular molecule interactions

Metabolic Pathway

begins with a specific molecule and ends with a product
chain of reactions
enzymes catalyze each step

Catabolic pathways

release energy by breaking down complex molecules into simpler ones
ex. cellular respiration

Anabolic Pathways

use energy to build complex molecules from simpler ones
ex. protein synthesis from amino acids

Bioenergetics

the study of how organisms manage their energy resources

Energy

the capacity to cause change
exists in various forms
some forms can perform work

Kinetic energy

energy associated with motion
Heat (thermal energy)
kinetic energy * associated with the random movement of atoms of molecules

Potential Energy

energy that matter possesses because of its location or structure

Chemical Energy

potential energy available for release in a chemical reaction

Thermodynamics

the study of energy transformations

Isolated System

isolated from its surroundings
ex. liquid in a thermos

Open System

energy and matter can be transferred between the system and its surroundings
ex. organisms

First Law of Thermodynamics

energy of the universe is constant
energy can't be created or destroyed, only changed
principle of conservation of energy

Second Law of Thermodynamics

during every energy transfer or transformation, some energy is unusable, and is often lost as heat
each change increases the entropy (disorder) of the universe

Spontaneous Processes

occur without energy input
they can happen quickly or slowly
increase entropy of the universe

Biological Order and Disorder

cells create ordered structures from less ordered materials
organisms replaced ordered forms of matter and energy with less ordered forms
energy flows into an ecosystem as light and out as heat

Exergonic Reaction

net release of free energy
spontaneous

Endergonic Reaction

absorbs free energy from its surroundings
nonspontaneous